Jim "Mattress Mack" McIngvale made what is believed to be the largest losing wager in horse racing history Saturday, as a $2.4-million win bet on Essential Quality (Tapit) went down in flames as the favorite in the GI Kentucky Derby finished fourth. But, for McIngvale, there were no wounds to be licked. The bet was tied into a promotion at his Gallery Furniture Stores in Houston. Anyone buying a mattress worth $3,000 or more prior to the Derby would get the mattress for free if the betting favorite won the...